One of the major problems in apparatus of the type to which the present invention pertains is to design a system which provides a large viewing screen, but yet which may be easily transported and installed, and which may be easily passed through a doorway. For example, in a typical system the viewing screen is 30 inches from the front to the back. Early designs of such systems have limited the outer dimension from front to back to approximately 32 inches. However, it is not possible to pass such prior art viewers through a doorway that is less than 32 inches wide.
It is the object of the present invention to provide an optical viewer which has a large screen, but yet which is collapsible to a size substantially smaller than the size of the screen so that the apparatus may be passed through a doorway that is narrower than the dimension of the screen. It is a further object of the present invention to provide such a collapsible apparatus which still maintains required optical rigidity for proper optical reproduction on the large viewing surface, which is easily manufactured, and which is easily collapsed and set up.